1. Field of the Invention
The present invention relates to a field emission device, and more particularly, to an aging apparatus of a field emission device capable of preventing arc by applying an alternating current pulse at the time of an aging operation.
2. Description of the Conventional Art
As an information processing system develops and widely spreads, an importance of a display device as a display information transmitting means is being spotlighted.
A cathode ray tube (CRT), one of the conventional display devices, has disadvantages that its size is large and an image display distortion due to an earth magnetic field is generated. Each kind of recent display device has a goal of a large screen, a flat screen, a high brightness, and a high efficiency. According to this, each kind of flat panel display device is being briskly researched. As the flat panel display device, a liquid crystal display (LCD) device, a plasma display panel (PDP) device, a field emission display (FED) device, and etc. are being developed.
Generally, the field emission display device has a region of a high vacuum for emitting an electron between an upper substrate and a lower substrate where a high voltage is applied, that is, between an anode and a cathode. When an FED vacuum tube is fabricated for construction of the high vacuum region, a small quantity of contaminants adhering to surfaces of emissive elements, faceplates, gate electrodes, spacer walls, and etc. can be generated. If a field emitting device including said contaminants therein is driven, electrons are bombarded with said contaminants thus to generate a phenomenon that particles of the contaminants are knocked off the surfaces.
According to said phenomenon, a high ionization pressure region is formed in the vacuum tube thus to catalyze an electron emission between a scan electrode and a gate electrode. A part of the emitted electrons is not emitted to the anode but hits the gate electrode, thereby overheating the gate electrode or badly influencing on a voltage difference formation between the gate electrode and an emitter electrode. When the gate electrode is overheated, a brightness discharge current exceeding an energy gap between a scan electrode and the gate electrode is formed thus to damage the scan electrode severely, thereby reducing a lifespan of the field emission device. This phenomenon is called as an arc.
In order to prevent said arc phenomenon, contaminants inside of a panel are removed and a pressure is lowered, that is, a high vacuum state is maintained.
Meanwhile, in order to remove contaminants of the conventional field emission device, getter for absorbing contaminants was included in the panel thus to absorb contaminants at the time of driving the field emission device.
However, the method for absorbing contaminants by getter is limited. That is, a capacity difference of getter is great according to a size of the field emission device, and contaminants can not be absorbed any more at a saturated state.
In order to solve said problems generated at the time of using getter, an aging operation using a direct current voltage is being performed recently to remove contaminants of a high vacuum region. That is, by applying a direct current high voltage which gradually increases to the anode, contaminants adhering to a surface of the high vacuum region are separated. The separated contaminants are exhausted to outside by a vacuum pump thus to remove contaminants.
However, according to the conventional aging method, when a direct current voltage is applied to the field emission device, very high energy is charged in the field emission device and arc due to a high electric field is frequently generated thus to damage the device and thereby to lower a lifespan.